1. Technical Field
The invention relates to glass having light protection properties, a method for manufacturing such glass and preferred applications of same.
2. Prior Art
Common glass offers only insufficient protection from the effects of light. In particular it lacks the sufficient capacity to absorb ultraviolet light. There is increasing demand for glass offering protection from the action of light, especially that of ultraviolet light. This applies all to clear or only slightly tinted glass used in the packaging of various foodstuffs, especially beverages such as beer, for example.
There are a number of known possibilities for creating glass which ensures protection from light action, in particular through the absorption of ultraviolet rays. In these types of glass the desired light protection properties are achieved by relatively costly methods. These kinds of known glasses capable of absorbing ultraviolet light are thus relatively expensive.
The invention is based on the objective of creating a cost-efficient glass with light protection properties, a simple method for manufacturing such glass and advantageous application of same.
A glass capable of absorbing in particular ultraviolet light for the purpose of solving the stated objective is characterized by a vanadium-containing aggregate. The addition of vanadium imparts UV-ray absorbing properties to the glass, thus making it light-protected. Through the use of an aggregate containing vanadium there is no need to use pure vanadium (vanadium oxide) but merely an economical aggregate containing vanadium oxide as one component among other components. Such and xe2x80x9cimpurexe2x80x9d aggregate is much more economical that pure vanadium oxide.
The aggregate is preferably a residual product containing vanadium oxide as the vanadium donor component. Such residual products arise during other manufacturing processes and can therefore be produced relatively economically.
A glass suitable for achieving the objective stated at the outset comprises the composition disclosed herein. Accordingly, vanadium pentoxide and phosphorous oxide are used for light protection, with vanadium pentoxide imparting to the glass the UV-ray absorbing properties, while phosphorous oxide is employed as a companion substance as a reasonable alternative to the use of the more expensive pure vanadium pentoxide. Here it has been shown that phosphorous oxide had not negative effects on the glass composition and in particular does not reduce the light-protecting properties of the glass. Preferably, the percentage of vanadium pentoxide and phosphorous oxide used is about the same.
Also provided by the invention is that the visual color impression of the transparent or translucent glass is kept as low as possible. It has been demonstrated that for this type of (transparent and colorless) glass, it is only with the addition of vanadium pentoxide that the light protection effect is possible of significantly effective in the first place.
A method for solving the objective stated at the outset is characterized in that a vanadium-containing aggregate is added to a batch of raw materials. Accordingly, during the production of the UV-ray absorbent glass a vanadium-containing aggregate is added to the raw materials. Through the use of the vanadium-containing aggregate, which is merely added to the raw starting materials, the glass according to the invention is especially economical and simple to produce. This is particularly true if, according to a further suggestion of the invention, a residual product is used as the vanadium-containing aggregate.
The residual product used as the aggregate requires a vanadium pentoxide content of only 40-60% by weight, in particular up to approximately 50% by weight, in order to achieve the desired light protection of the glass. Therefore a relatively impure residual product or aggregate can be used.
Preferred applications for solving the objective stated at the outset include containers for foodstuffs; a transparent glass or a transparent bottle for foodstuffs, in particular for beverages; and a transparent bottle, in particular a colorless or essentially colorless transparent bottle, preferably a beer bottle. Accordingly, a glass as disclosed herein is particularly suited for making containers for foodstuffs. These may be jars or bottles.
A further preferred application of the glass as disclosed herein relates to a glass or a bottle for foodstuffs.
One particularly advantageous application for the glass as disclosed herein is directed towards a bottle for beverages, in particular for beer. The glass as disclosed herein can be preferably used for a colorless or neutral-colored transparent bottle for beer, specifically for beer containing alcohol as well as for alcohol-free beer, or other beverages.